1. Field of the Invention
The present invention relates to a scroll compressor and, more particularly, to a scroll compressor which can prevent damage due to expansion of a dust seal with an increase in temperature and, at the same time, reduce noise by absorbing vibration of a self-rotation preventing mechanism.
2. Description of the Related Art
In general, a scroll compressor comprises an orbiting scroll supported on an eccentric shaft portion of a drive shaft and a stationary scroll including a stationary end plate having a stationary wrap.
An orbiting wrap on an orbiting end plate of the orbiting scroll is engaged with the stationary wrap to form a sealed chamber between the stationary wrap and the orbiting wrap.
Moreover, the scroll compressor comprises a self-rotation preventing device for preventing the orbiting scroll from rotating on its own axis.
By the eccentric shaft portion of the drive shaft and the self-rotation preventing device, the orbiting scroll is eccentrically revolved such that the volume in the sealed chamber gradually decreases toward the center to be compressed or gradually increases away from the center to be depressurized to discharge from the outer circumference.
Meanwhile, the ends of the orbiting and stationary wraps have engagement grooves in which tip seals being in sliding contact with the opposing end plates are fitted sealingly, and the tip seals are fitted in the engagement grooves.
Moreover, in the scroll compressor, a dust seal on the outer circumference of an engagement area of the orbiting and stationary wraps.
A representative example of this scroll compressor is disclosed in patent document 1 (hereinafter referred to as “prior art 1”).
However, the dust seal and the tip seals of the scroll compressor prior art 1 have the following problems:
(a) Circle
The circular dust seal fitted in an annular groove requires very precise dimensions and significant efforts and techniques. Moreover, heat or lateral pressure generated during operation stretches the dust seal or deforms the annular groove to cause unsuitable fitting. Deviation of the dust seal in the annular groove causes failure in sealing;
(b) Partially Separated Circle Whose Ends are in Contact with or Close to Each Other
To absorb thermal expansion of the dust seal, a slight gap is formed between the ends in advance. However, it is impossible to completely prevent dust from entering through the gap. To prevent this, the ends of the dust seal are tilted or overlapped: which is cumbersome and expensive. The dust seal tends to move in the annular groove toward the periphery;
(c) Partially Separated Circle Whose Ends are in Contact with the Outer Surface of the Outermost Tip Seal
The annular groove must be formed into a non-circular shape, which is not so easy to achieve. During operation, a gap is formed between the end of the dust seal and the outer surface of the tip seal, and thus dust enters through the gap; and
(d) When the Tip Seals are Worn Due to Sliding Contact, the Sealability is Reduced.
Moreover, the scroll compressor comprises a self-rotation preventing mechanism for preventing the orbiting scroll from rotating on its own axis.
Furthermore, by the eccentric shaft portion of the drive shaft and the self-rotation preventing device, the orbiting scroll is eccentrically revolved such that the volume in the sealed chamber gradually decreases toward the center to be compressed or gradually increases away from the center to be depressurized to discharge from the outer circumference.
A representative example of this scroll compressor is disclosed in patent document 2 (hereinafter referred to as “prior art 2”).
However, the scroll compressor of prior art 2 does not disclose a means for reducing vibration generated by the revolution of a self-rotation preventing eccentric shaft of the self-rotation preventing mechanism.
Therefore, the noise due to the vibration increases, and the durability of the scroll compressor is reduced.
Moreover, in the scroll compressor of prior art 2, a bearing tube for supporting a bearing installed in the drive shaft is integrally formed with a housing.
Therefore, when the housing is made of aluminum alloy, the bearing tube is thermally expanded during operation of the scroll compressor, which reduces the force for supporting a ball bearing, causing the ball bearing to rotate in the bearing tube.
When the housing is made of cast iron to prevent the rotation of the ball bearing in the bearing tube, the force for supporting the ball bearing is sufficient, but the total weight of the scroll compressor increases, which is problematic.
To solve the above problem, a scroll compressor in which the housing is made of aluminum alloy and the bearing tube is made of cast iron is disclosed in patent document 3 (hereinafter referred to as “prior art 3”).
However, in the scroll compressor of prior art 3, the bearing tube supporting the drive shaft is detachably assembled to the housing and is fixed to the housing with a bolt, and thus the number of assembling processes increases, which is problematic.
Moreover, the number of total processes such as processing for the bolt connection area between the housing and the bearing tube, etc. increases, and thus the manufacturing cost of the scroll compressor increases.
Therefore, there is a need to develop a scroll compressor which solves the problem due to the thermal expansion of the dust seal, increases the sealing force of the tip seals, reduces the noise due to the vibration of the self-rotation preventing mechanism, and solves the problem due to the thermal expansion of the bearing tube.
Patent document 1: U.S. Pat. No. 6,695,597 (Anest lwata Corporation) 2004.02.24
Patent document 2: Korean Patent Publication No. 2007-0049556 (2007.05.11)
Patent document 3: Korean Patent Publication No. 2006-0045343 (2006.05.17)